1. Field of the Invention
The present invention relates to a scan driver, a light emitting display including the same, a driving method thereof, and more particularly, to a scan driver, a light emitting display including the same, and a driving method thereof, in which the number of wiring lines is decreased, and the number of output lines connected to a scan driver is decreased, thereby enhancing an aperture ratio and reducing power consumption.
2. Discussion of Related Art
Recently, various flat panel displays have been developed to replace cathode ray tube (CRT) displays because the CRT displays are relatively heavy and bulky. Among the flat panel displays, a light emitting display is notable because it has high emission efficiency, high brightness, a wide viewing angle, and a fast response time.
The light emitting display includes a plurality of light emitting devices, wherein each light emitting device has a structure in which an emission layer is placed between a cathode electrode and an anode electrode. Here, electrons and holes are injected into the emission layer and recombined to create excitons, and light is emitted when an exciton falls to a lower energy level.
Such a light emitting display is classified into an inorganic light emitting display including an inorganic emission layer, and an organic light emitting display including an organic emission layer.
FIG. 1 is a circuit diagram of a pixel provided in a conventional light emitting display. Referring to FIG. 1, four pixels are adjacent to each other, and each pixel includes a light emitting device (e.g., organic light emitting diode (OLED)) and a pixel circuit. The pixel circuit includes a first transistor M1, a second transistor M2, a third transistor M3, and a capacitor Cst. Here, each of the first through third transistors M1, M2 and M3 has a gate, a source and a drain; and the capacitor Cst has a first electrode and a second electrode.
Every pixel has the same configuration, and thus a top left pixel will be exemplarily described hereinbelow. The first transistor M1 includes the source connected to a power line Vdd, the drain connected to the source of the third transistor M3, and the gate connected to a first node A. The first node A is connected to the drain of the second transistor M2. Here, the first transistor M1 supplies current corresponding to the data signal to the light emitting device OLED.
The second transistor M2 includes the source connected to a data line D1, the drain connected to the first node A, and the gate connected to a first scan line S1. Here, the second transistor M2 receives a first selection signal through its gate and supplies the data signal to the first node A.
The third transistor M3 includes the source connected to the drain of the first transistor M1, the drain connected to an anode electrode of the light emitting device OLED, and the gate connected to an emission control line E1 to respond to an emission control signal. Here the third transistor M3 controls the current flowing from the first transistor M1 to the light emitting device OLED in response to the emission control signal, thereby controlling the light emitting device OLED to emit light.
The capacitor Cst includes the first electrode connected to the power line Vdd, and the second electrode connected to the first node A. Here, the capacitor Cst stores electric charges corresponding to the data signal, and supplies a signal based on the stored electric charges to the gate of the first transistor M1 for one frame, thereby maintaining an operation of the first transistor M1 for one frame.
However, in the pixel provided in the conventional light emitting display, the emission control lines are connected to pixel rows, respectively. Therefore, the number of wiring lines is proportional to the number of emission control lines, thereby deteriorating an aperture ratio.
Further, in this case, the scan driver outputs the emission control signal to the plurality of emission control lines, and therefore, the number of output lines connected to the scan driver increases in proportion to the number of emission control lines, thereby increasing the number of components provided in the scan driver. Therefore, the power consumption increases in the scan driver. Further, the size of the scan driver is increased, thereby wastefully occupying much space of the light emitting display.